Cycloalkenes, preferably cycloalkadienes having a ring size of from 12 to 18 carbon atoms, are used, inter alia, for preparing oxygen-containing, macrocyclic compounds. The compounds can be used in the preparation of macrocyclic ketones, lactones and epoxides, which are prized as musk fragrances in the perfume industry.
EP-A 182 333 discloses the catalyst system Re2O7/γ-Al2O3/SnR4, where R is an alkyl radical, which can be used for converting highly diluted cycloolefin solutions in the liquid phase into the corresponding cycloalkadienes by a metathesis reaction.
The preparation of cycloalkadienes in the liquid phase in the presence of a supported catalyst based on Re2O7/γ-Al2O3 by a metathesis reaction of cyclooctenylenes having a degree of polymerization greater than, or equal to three, and/or cycloalkamonoenes is described in EP-A 343 437.
The metathesis of methyl oleate using the catalyst system Re2O7/γ-Al2O3/SnR4 is described in Applied Catalysis 1991, 67, 279. The pore volume of this pulverulent catalyst was 0.48 g/cm3 at an Re2O7 content of 3.1%.
The metathesis of unsaturated esters over Re2O7/γ-Al2O3 catalysts is known from Journal of Molecular Catalysis 1985, 28, 141. The pore volume of this pulverulent catalyst was 0.36 g/cm3 at an Re2O7 content of 5.0%.
Metathesis catalysts based on Re2O7/γ-Al2O3 are described in Catalysis Letters 1991, 8, 201. A 180–250 μm aluminum oxide particle fraction was doped with 2.2% by weight of phosphorus by digestion. The pore volume of this pulverulent support material was 0.38 g/cm3 without a Re component.
Due to the necessarily high dilution of the cycloolefin solutions used in the metathesis reaction, the amount of cycloalkadienes obtainable per unit time has been unsatisfactory from economic, engineering and industrial points of view.